The Constitution of the United States of Mexico (1917) at Art. 22 states:

The Constitution of the United States of Mexico (1917) at Art. 22 states: "The death penalty is prohibited for political crimes, and, in relation to other crimes, can only be imposed for treason during international war, parricide, first degree murder, arson, kidnapping, banditry, piracy and grave military offences."
The preceding offences were considered a threat to society when the Constitution was first introduced, and now have a symbolic function. The death penalty cannot be applied, in fact, because it is not included in any state or federal code.
The military penal code was the only part of Mexico’s statutes that still effectively allowed for the application of capital punishment.
But on April 21, 2005, Mexico’s Chamber of Deputies approved a bill abolishing the death penalty under military jurisdiction and replacing it with prison terms ranging from 30 to 60 years. With 346 votes in favour, none against, and three abstentions the plenum ratified the amendments to the Code of Military Justice which had already been approved by the Senate in April 2004.
In September 2003, the Mexican government moved to remove the reference to the death penalty from the Constitution, as the Commission of Government Policy on Human Rights Matters, led by the President of the Republic, decided to lend its support to initiatives presented in Congress towards this end. On March 31, 2004 President Vicente Fox, a firm abolitionist, sent the Senate a bill aimed at abolishing the death penalty under military jurisdiction. The Code of Military Justice allowed the death penalty for serious crimes including treason, premeditated murder and arson, but executions have not been carried out since 1961, due to an informal tradition under which presidents commute capital sentences. Fox intervened in November 2003 to spare two soldiers sentenced to death by military tribunals for killing superiors. The Senate backed the president’s proposal in April 2004, but this had to be approved also by the Chamber of Representatives, dominated by the opposition, before it could become law.
On June 23, 2005, Mexico's House approved a measure striking the death penalty from the constitution and inserting language expressly prohibiting capital punishment. By a vote of 412-0, with two abstentions, lawmakers passed a measure approved on March 18 by the Senate. The amendment modified Articles 14 and 22 of the constitution eliminating the possibility of issuing a sentence of death for all the crimes the penalty had been provided for. The amendment had only to be passed by legislatures in a majority of the nation's 31 states, where it was expected to face little opposition, following which even the theoretical possibility of sentencing someone to death would disappear from Mexico’s legislation.
The last execution in Mexico took place in 1961, when a soldier, Isaías Constante Laureano, was put to death for the murder of an officer in Saltillo Coahuila.
In 2001, in a landmark ruling, Mexico's Supreme Court said for the first time that citizens could be extradited as long as potential punishment did not include life prison terms or the death penalty. Mexican law has no provisions for either penalty.
On March 31, 2004, the International Court of Justice upheld an appeal presented by Mexico in 2003 and ordered the United States to review the cases of 51 Mexican nationals on death row in ten US states. The Court established that the US violated the 1963 Vienna Convention on Consular Relations by not informing the accused of their right to legal assistance from their own consulate.